The present invention relates to the field of augmentor liners, particularly those used in aircraft combustion chambers.
Augmentor liners provide acoustic surpression of high cycle combustion instability, commonly known as screech, which may be defined as intense combustion induced, high frequency pressure oscillations which, under certain conditions, are generated in the augmentor. See U.S. Pat. No. 4,833,881. In conventional liners, this is achieved by providing screech holes in the liner. The hole area and underliner volume determine the screech absorption characteristics. The hole area required is usually much more than would be required to cool the liner so that much air is used inefficiently.
It is deemed desirable to provide means for absorbing screech which at the same time restricts the flow rate of cooling air so that less fan air is "used" by the liner and more is thus available for cooling use elsewhere.